Robert E. Diamond Jr., a fiercely competitive Wall Street executive who hated to lose, recognised late Monday night that he was losing.

Robert E. Diamond Jr., a fiercely competitive Wall Street executive who hated to lose, recognised late Monday night that he was losing.

Until then, the American-born chief executive of the British banking giant Barclays was convinced that he could survive the rising calls for his ouster after accusations from regulators in Britain and the US that Barclays had manipulated important global interest rates with the knowledge of senior management.

On Monday, the 60-year-old executive wrestled with the pressures confronting his bank from regulators and politicians. Realising that he had become a lightning rod, Diamond decided to resign, according to a person with direct knowledge of the matter.

“My motivation has always been to do what I believed to be in the best interests of Barclays,” Diamond said on Tuesday. “The pressure has reached a level that risks damaging the franchise. I cannot let that happen.”

It was an abrupt downfall for a man who over two decades had built an investment banking powerhouse nearly from scratch.

Diamond, who grew up near Boston but eventually became a British citizen, brought American flair to the stodgy world of British banking. Charming, with a gleaming smile, he was a relentless promoter of the Barclays brand, attaching it to golf outings, soccer leagues and even to London’s new public bicycle rental system. But his embrace of the American-style pay and bonus culture became one of his main vulnerabilities.

He paid his people, from whom he demanded and usually got unstinting loyalty, extremely well — and he was very well rewarded himself.

Diamond was awarded £6.3 million, or $10.3 million, in pay and perks for last year. The pay of two of his top executives, Jerry del Missier and Rich Ricci, has not been officially disclosed.